The present invention generally pertains to an intercooler for manifold intake air. More particularly, the present invention relates to an intercooler arrangement for a turbocharged or supercharged motor vehicle engine having a charge air cooler fluid loop to which additional cooling capacity is provided via a bypass circuit from the vehicle air conditioning system.
The terms xe2x80x9cturbochargingxe2x80x9d and xe2x80x9csuperchargingxe2x80x9d both refer to methods of increasing the air or air/fuel mixture density of a motor vehicle engine by increasing the pressure of the intake air stream prior to its entering the engine cylinder. Increasing the density of air in the cylinder is desirable because it represents a relatively simple method of increasing the power generated by the engine. Turbocharging generally means that the air intake compressor is powered by the engine exhaust stream. Supercharging generally means that the air intake compressor is powered by coupling it to the engine via a belt, chain, gear(s), etc. Turbocharging is often favored over supercharging because current designs are more efficient at harvesting the energy in the exhaust stream. This increased efficiency currently means that turbocharging permits an increase in the engine power output without a significant decrease in fuel economy. The term, xe2x80x9cchargerxe2x80x9d and xe2x80x9cchargingxe2x80x9d is used herein to refer to both turbochargers and superchargers.
Since pressure is directly related to heat, as the charger increases the pressure of the intake air stream it also increases its temperature. It is well known that cooling this intake air stream further permits an additional increase in its pressure since cooler air can be more densely packed. This additional cooling is generally accomplished through the use of an intercooler.
The simplest intercooler involves incorporating a heat exchanger into the air stream between the charger and the engine intake manifold. Such a heat exchanger can incorporate fins, coils, or a combination thereof to improve the rate at which heat is absorbed and re-radiated into the ambient environment. However, even if the placement and plumbing of the heat exchanger are optimized the ambient air temperature as well as the temperature at the air intake point represent uncontrollable variables.
U.S. Pat. No. 4,683,725 to Sugiura; U.S. Pat. No. 5,435,289 to Pendlebury, et al.; and U.S. Pat. No. 6,394,076 B1 to Hudelson; all describe designs that eliminate the problems of a passive intercooler loop. Each of these patents describes an intercooler located in the intake air stream between the charger and the combustion chamber where the intercooler contains a heat exchanger that is cooled by the vehicle""s air conditioning system. These designs permit reasonably uniform cooling of the intake air stream. However, the need for maximum cooling of the intake air stream and the passenger compartment are most likely to occur simultaneously. In the best case, this significantly reduces engine efficiency and erases the power gains from charger/engine combination. In the worst case, failure of the air conditioning, charger, and/or engine can result.
Motor vehicles have been increasing in complexity since Henry Ford ushered in the age of manufactured vehicles. With each successive model year an increasing number of features that contribute to the performance, safety, and operator comfort have been incorporated into vehicles. Features that were once optional are now standard equipment. Probably the only negative aspect of this trend is ever diminishing space in the engine compartment. Thus, it is most desirable for components that improve engine performance to be compact and retain their functionality no matter where they are mounted in the engine compartment.
Compared to a charger, an intercooler is a simple and relatively inexpensive component. With this fact in mind, it would seem that the use of an intercooler would generally be easy to justify because its contribution to the operating efficiency of the charger is greater than its expense, size, and weight. While simple intercoolers are found on many turbocharged vehicles, improved intercoolers, such as described above, have not been adopted for production vehicles. It appears that this is because their contribution to improved vehicle performance is outweighed by their expense, size, and weight compared to the simplest intercooler or no intercooler at all. Thus, it would be advantageous to provide an improved intercooler design that would be inexpensive and small, yet still capable of significantly increasing the efficiency of the charger.
One object of the present invention is an improved intercooler arrangement for a motor vehicle that is inexpensive, efficient, and relatively small.
Another object of the invention is an intercooler that is adaptable to a variety of engine sizes and configurations and capable of efficiently cooling the intake air stream.
These and other objects are satisfied by an intercooler for a vehicle engine incorporating an exhaust gas turbocharger and an air conditioning system, the intercooler comprising: a charge air cooler loop operatively connected to cool heated, pressurized air from the turbocharger before it flows into the vehicle engine; and an air conditioning system bypass loop operatively connecting the air conditioning system to the charge air cooler loop.